Author(s): L. Guiot; L. Cassan; G. Belaud

Linked Author(s): Gilles Belaud

Keywords: Tide gate; Sluice gate; Water resource management; Fish passage

Abstract: In many coastal marshes, hydraulic structures are widely used to prevent from flooding and salt intrusion in coastal areas. However, these structures (tide gate, sluice gate, weir) are an obstacle to fish passage and cause the disconnection of water bodies. In this paper, we investigate the case of a fresh marsh network linked to the sea by a tide gate. The objective is to explore management strategies of hydraulic structures in order to improve fish passability by increasing the duration of “fish-friendly” periods. The study area is located at the mouth of Charente River (France, Atlantic Ocean coast), an area with a high potential for European Eel growth. The marsh consists of ponds separated by sluice gates and weirs, and 4 lateral tributaries used for irrigation and drainage. To determine if a fish can pass through a hydraulic structure (tide gate or sluice gate), local hydraulic conditions need to be considered and compared to maximum swim speed of fish species. If the swim speed of a given chosen fish species (European Eel) is lower than to the mean velocity through the gate, then the gate cannot be passed. A simple management strategy was to put a block on the gate in order to avoid the complete closing of the tide gate, and so let a slot for fish passage. The consequence is an increase of sea water intrusion within the network, causing a decrease of water level difference and then a less efficient drainage.

DOI: https://doi.org/10.15142/T34645

Year: 2018